The good news. I had the 200mph speedometer gauge faces made for the newer style speedometers and have 6 of them on hand.
 The bad news. I went off of my own assumptions that I should be able to modify the newer style speedometer boards to calibrate them for the 200mph gauge face without much effort. I was wrong! I never looked closely at the electronics until I received the gauge faces. Big mistake! After spending two days examining and analyzing the board I only now understand how it works. Don't know if anyone has ever looked at the newer style boards or not but if you have you'll notice that there are no adjustable resistors and very few components. The reason is, these boards use a dedicated chip that was designed to do all the speed signal conversions for either MPH or KPH. The boards actually have three chips. The first chip (IC1) receives the signal and splits the direction in four. One signal is an analog voltage output which is linear to the amount of speed input. This connection is not used but can be used for the iECU project I'm working on for speed display. Good! A second signal is output to a second IC chip which is used for sending the stepper voltages to the odometer stepper motor. The third signal out is sent to the ECU to tell it your speed (a 2 pulse signal). The forth signal output is sent to the third IC where it's pin configuration is hardware configured via the circuit board traces to display either MPH or KPH depending on what gauge cluster the speedometer board is in (USA/UK or JDM/Other). A good thing I found is that if you can't find a USA gauge cluster for use in replacing a bad speedometer board you can use a KPH gauge cluster and modify it's speedometer board to display MPH with little effort. I'll probably put a write-up on how to convert a JDM gauge for use in a USA cluster later. I've already taken pictures of a conversion I did which can be used in the write-up. So, the bad thing about the way the new boards work is that the dedicated speed calculating IC cannot be altered in the way it works to display the speed. The external components on the board are only for powering the chips and sending the 2 pulse signal to the ECU. Any conversion of the signal would have to be done before it's input to the board. To sum it up, I may end up taking a loss on the gauge faces I already had made. But, I'm not giving up yet. An alternative I'm looking at is a circuit to modify the signal before it's input to the gauge. The bad thing about this I don't like is that it will add cost to the conversion and require an external device. Since I have other priorities going on, the newer style 200 mph gauge modification is on hold for now. Sorry!
 www.mytwinturbo.com Nissan Data Voice - The first Nissan diagnostic software with a voice!
 Nissan Data Voice on YouTube Download my Nissan 300ZX Vin/Model Lookup. Watch an ECZA meet caravan! |
Good/Bad news regarding the new style 200 mph gauges. - 
